In the recent years, many machine tool manufacturers have introduced five-axis machine tools, lathe and milling complex machine tools equipped with intelligent system. For machine tools, the way for preventing collision between mechanism moving elements is an important issue. Increase in complexity of mechanism and machining curved surfaces along with problems in programming will cause over cutting easily and even damages of tools and workpieces. Additionally, after collision between mechanism moving elements, the precision of mechanism elements may be reduced so that it is difficult to adjust back to original condition.
Therefore, the development of preventing collision devices is highly demanded. Devices for preventing collision are classified into a hardware for monitoring and preventing collision and a three-dimensional (3D) preventing collision software. The hardware for monitoring and preventing collision includes sensors installed at certain positions and signals are sent back to controllers to carry out corresponding measurements for preventing collision. The 3D preventing collision software employs hierarchical boundary area computing to design mechanisms for preventing collision; and to adjust the size of 3D envelope volume based on related machine information and machining conditions such that the probability of collision may be predicted to send out alarms to interrupt the machining.
However, the length of tool and the offset relative to the datum mark of tool seat have to be set in the 3D preventing collision software from the user end in order that the 3D preventing collision software is able to draw the geometrical relationship between the tool and the machine precisely, and interference inspection is carried out based on the machining procedures. Therefore, it is very inconvenient for users. Furthermore, a gripper and a cutting machine are usually included in a conventional machine tool system. The gripper is used for gripping a workpiece such that the workpiece can be machined. The cutting machine has a plurality of tool seats. Tools are installed in the tool seats when using the machine tool system. And the tool in one of the tool seats is selected for machining the workpiece.
Before performing machining, a simulation unit is used for simulating the conditions of the workpiece being machined by the tool. Afterwards, the tool is used to machine the workpiece based on the simulation results. However, when the tool is installed in the tool seat, offset errors may occur in the installation. Therefore, imprecise simulation results may occur during the simulation process. Even more imprecise machining results may occur if the workpiece is machined by the tool based on these simulation results. Different offset errors may also exist in the tools in each of the tool seats. Errors of the workpiece will greatly increase after being machined by various different tools. Therefore, failed machined products are produced.